This invention relates to transparent thermoplastic compositions having improved processability, improved mar resistance and reduced friction. In applicant's copending application entitled "Non-bleeding Transparent Silicone Additives For Plastics," executed May 30, 1980, there is disclosed and claimed copolymers of monophenylsiloxane and dimethylsiloxane which are compatible with clear thermoplastics and which improve the lubricity and processability of those materials. The instant invention relates to reaction products of phenylsilanes with the glycol 2-methyl-2,4-pentane diol which are cheaper than the compositions of the aforesaid copending application. The compositions used in the instant invention also give clear thermoplastics with improved lubrication and processability.
Minor amounts of polydimethylsiloxane fluids are often admixed with thermoplastics to provide the thermoplastic with beneficial properties such as reduced friction and wear. Many such internally lubricated thermoplastic compositions have achieved considerable commercial success due to the improved properties obtained with minimal cost. However, admixtures of polydimethylsiloxane fluids and thermoplastic polymers are not useful when transparent thermoplastic objects are desired because of the imcompatability of the polydimethylsiloxane with thermoplastic polymers. This incompatibility results in admixtures that are opaque or milky white in appearance even at very low levels of polydimethylsiloxane.
For example, U.S. Pat. No. 3,087,908 discloses that polydimethylsiloxane gives detectable haze in polycarbonate films at concentrations as low as 200 parts per million with significant haze occurring at siloxane concentrations above 400 parts per million. While these low concentrations may provide some enhancement of film-forming properties, they are not sufficient to provide the major processing and wear benefits of internal lubrication. As disclosed by U.S. Pat. No. 2,999,835, such benefits are obtained in polycarbonates at siloxane concentrations above 1000 parts per million or even preferably, at or above 10,000 parts per million. Similar results have been observed in other thermoplastic polymers.
It is a purpose of the present invention to provide internally lubricated transparent thermoplastic compositions. Further, it is a purpose of the present invention to provide an organosilicon compound that is compatible with thermoplastic polymers at concentrations appropriate for effective internal lubrication. Still another purpose of the invention is to provide a compatible organisilicon compound that can provide internal lubrication in thermoplastic polymers comparable with that obtained with polydimethylsiloxanes.